Feasibility and Safety of Treosulfan, Melphalan, and Thiotepa-Based Megachemotherapy with Autologous or Allogeneic Stem Cell Transplantation in Heavily Pretreated Children with Relapsed or Refractory Neuroblastoma.

The prognosis of resistant or relapsing children with neuroblastoma remains very poor, and the search for new therapies is ongoing. In this analysis, we assessed the toxicity of a treosulfan, melphalan, and thiotepa (TMT) regimen in 17 children with recurrent or refractory neuroblastoma who underwent stem cell transplantation (SCT). For allogeneic SCT, fludarabine and antithymocyte globulin were added. The stem cell source was autologous in 8 patients, haploidentical in 8 patients, and a matched unrelated donor in 1 patient. The reported nonhematologic toxicities included grade 3 mucositis, grade 1 to 3 hypertransaminasemia, and in 3 patients, veno-occlusive disease. No neurologic, cardiac, or dermatologic toxicities were observed. The probability of overall survival (OS) in patients with primary resistance was superior to that in patients with relapsed disease (100% versus 22.6%; P = .046). Post-transplantation dinutuximab beta immunotherapy was associated with superior 5-year OS (66.7% versus 11.4%; P = .0007). The use of an allogeneic donor, previous autologous SCT with busulfan and melphalan, and pretreatment with high-dose metaiodobenzylguanidine therapy demonstrated no effect on outcomes. In 4 patients, TMT megatherapy alone was enough to achieve complete remission. The TMT conditioning regimen was well tolerated in heavily pretreated patients with neuroblastoma. The manageable toxicity and addition of new anticancer drugs with optional post-SCT immunotherapy or chemotherapy support further trials with the TMT regimen in patients with neuroblastoma.

Safety and efficacy of autologous mononuclear cell and stem cell apheresis in very low-weight children-Experience at a single center.

BACKGROUND: Apheresis in children with low body weight is technically limited by their tolerance of the extracorporeal blood volume. STUDY DESIGN AND METHODS: This paper presents a single-center experience with 23 procedures in 12 children with weights between 5.2 and 9.5 kg using the Spectra Optia mononuclear cell (MNC) protocol with blood priming. RESULTS: The average procedure duration was 158 minutes, and the median processed blood volume was 316 mL/kg. The white blood cell (WBC), platelet (PLT), and hemoglobin (HGB) values showed a downward trend with increased volume of processed blood. The post-apheresis HGB concentration was increased in all procedures due to initial priming with packed red blood cells (PRBCs), but this effect disappeared at a level of ~400 mL of processed blood/kg. The median volume of the cellular product was 36 mL, the WBC count was 153 K/µL, the hematocrit (HCT) was 1.5%, the PLT count was 602 K/µL, the WBC collection efficacy (CE2) was 13.2%, and the PLT CE2 was 9.5%. The median CD34+ CE2 was 28%, and interpolation of the CD34+ CE2 yielded a Y-intercept value of 32%. Higher pre-collection CD34+ counts resulted in higher CD34+ yields. No correlation was found between the pre-collection CD34+ results and CD34+ CE2. CONCLUSION: The analyzed data demonstrated the feasibility and safety of apheresis in very low-weight children. The laboratory abnormalities were asymptomatic and citrate toxicity was mild. Visual control of clogging with manual adjustment of the citrate infusion rate is important to reduce exposure to citrate.

Case Report: Liver as a Source of Hematopoietic Stem Cells After Liver Transplantation Following Hematopoietic Stem Cell Transplantation.

We report a child with Fanconi anemia who, after hematopoietic stem cell transplantation (HSCT) complicated by acute graft-versus-host disease (GVHD), underwent orthotopic liver transplantation (OLT). Approximately 1 month after OLT, the presence of third-party genetic material from the liver donor was noted and in the next few weeks, the chimerism assessment revealed 100% liver donor leukocytes in the peripheral blood. The rapidly progressing GVHD with gut involvement resulted in patient's death 6 months after OLT. The liver can act as a clinically significant source of hematopoietic stem cells, and the liver donor's young age must be emphasized as potentially predisposing to this phenomenon. Transfer of OLT hematopoietic stem cells may not have clinical significance unless the patient is not immunocompetent or develops liver-transplantation associated GVHD, that can result in lymphocyte mediated elimination of original hematopoiesis. Patients with preexisting immunity disorder (such as primary or secondary immunodeficiency) might require intensified immunosuppressive therapy in peritransplant period as a prevention of liver-transplantation associated GVHD. Close monitoring of hematopoietic chimerism after OLT is warranted in patients at risk, because cytopenia or OLT hematopoiesis can reflect subclinical GVHD and further studies are necessary to elucidate this phenomenon.

Fludarabine-Cyclophosphamide-Based Conditioning with Antithymocyte Globulin Serotherapy Is Associated with Durable Engraftment and Manageable Infections in Children with Severe Aplastic Anemia.

Severe aplastic anemia (SAA) is a bone marrow failure syndrome that can be treated with hematopoietic cell transplantation (HCT) or immunosuppressive (IS) therapy. A retrospective cohort of 56 children with SAA undergoing transplantation with fludarabine-cyclophosphamide-ATG-based conditioning (FluCyATG) was analyzed. The endpoints were overall survival (OS), event-free survival (EFS), cumulative incidence (CI) of graft versus host disease (GVHD) and CI of viral replication. Engraftment was achieved in 53/56 patients, and four patients died (two due to fungal infection, and two of neuroinfection). The median time to neutrophil engraftment was 14 days and to platelet engraftment was 16 days, and median donor chimerism was above 98%. The overall incidence of acute GVHD was 41.5%, and that of grade III-IV acute GVHD was 14.3%. Chronic GVHD was diagnosed in 14.2% of children. The probability of 2-year GVHD-free survival was 76.1%. In the univariate analysis, a higher dose of cyclophosphamide and previous IS therapy were significant risk factors for worse overall survival. Episodes of viral replication occurred in 33/56 (58.9%) patients, but did not influence OS. The main advantages of FluCyATG include early engraftment with a very high level of donor chimerism, high overall survival and a low risk of viral replication after HCT.

Successful Bone Marrow Recovery After an Immunoablative Regimen With Autologous Cord Blood Transplant in a Child With Idiopathic Severe Aplastic Anemia: A Case Report.

BACKGROUND: Aplastic anemia is a rare disease that manifests as bone marrow failure. The current treatment options include immunoablative therapy or allogeneic hematopoietic stem cell transplantation. We report a successful immunoablative regimen with autologous umbilical cord blood (auto-UCB) transplant in a 3-year-old boy with severe aplastic anemia. CASE REPORT: The immunoablation procedure consisted of 5 × 3.75 mg/kg antithymocyte globulin (Thymoglobulin) (total 18.75 mg/kg), methylprednisolone for 4 days, and cyclosporine A. The patient received auto-UCB containing 0.3 × 105 CD34+ cells per kilogram of body weight. Recovery of leukocyte count above 1000/µL was reached on post-transplant day +39, and recovery of granulocytes above 500/µL was reached on day +40. The final regular transfusions of packed red blood cells and platelet concentrate were performed on day +55. The complications that occurred in the post-transplant period were nausea, diarrhea, septic fever, and hepatic abscess formation. Post-transplant immunosuppression with cyclosporine A was discontinued 17.5 months after auto-UCB, and the patient remained in complete remission with normal blood counts and bone marrow morphology. SUMMARY: Auto-UCB transplantation without chemotherapy conditioning can be considered a therapeutic option for children with stored cord blood cells.

Successful Salvage Treosulfan-Based Megachemotherapy With Allogeneic Stem Cell Transplantation in Nonsyndromic, Therapy-Resistant Disseminated Juvenile Xanthogranuloma: A Case Report.

Juvenile xanthogranuloma (JXG) is a rare histiocytic disorder classified as non-Langerhans cell histiocytosis; although it is usually a benign and self-limiting disease, it can be fatal in some cases, especially with systemic dissemination. We present a case report of a boy with therapy-resistant disseminated JXG who was treated with systemic chemotherapy and received 3 allogeneic hematopoietic stem cell transplantations (allo-HSCTs) from an unrelated donor. The post-transplant period was complicated by acute graft vs host disease and lymphoproliferative disease caused by Epstein-Barr virus. Currently, almost 7.5 years after the first transplantation, the boy is in complete remission with full donor chimerism and without symptoms of JXG. The presented data confirm rare observations that allo-HSCT can lead to durable remission of systemic JXG, which warrants its use in life-threatening, therapy-resistant subtypes of disease.

Pediatric unmanipulated haploidentical hematopoietic stem cell transplantation with post-transplant cyclophosphamide and reduced intensity, TBI-free conditioning regimens in salvage transplantations.

BACKGROUND: Unmanipulated haploidentical stem cell transplantation (haploSCT) with post-transplant cyclophosphamide is an option for patients with advanced hematologic malignancies. It offers a platform both for non-major histocompatibility complex-restricted alloimmunity due to killer-like immunoglobulin receptor (KIR)-mediated mechanisms of natural killer lymphocyte regulation and for classical T-cell mediated antileukemic effects. OBJECTIVES: The devastating long-term sequelae after total body irradiation (TBI) in children are encouraging omission of irradiation techniques in pediatric stem cell transplantations (SCT). MATERIAL AND METHODS: Five children, 4 with acute leukemia and 1 with hemophagocytic lymphohistiocytosis, aged from 1 to 10 years, underwent haploSCT with post-transplantation cyclophosphamide. In all children, the conditioning regimen consisted of chemotherapy without TBI. The graft material was bone marrow (BM) in 4 cases and peripheral blood stem cells in 1 case. Three out of 5 leukemic patients showed better KIR haplotype associated with augmented alloreactivity. RESULTS: Engraftment with complete donor chimerism was achieved in 4 patients, and 1 recipient died before leukocyte recovery. Three patients developed skin acute graft-versus-host-disease (aGvHD), 1 gut aGvHD and 1 liver aGvHD. In 2 recipients, chronic graft-versus-host-disease (cGvHD) was observed (1 limited and 1 extensive). The 4 engrafted patients were alive and in complete remission 3, 9, 32, and 36 months after transplantation. A T-cell count of 200 cells/uL was reached 90 days after haploSCT in all patients. CONCLUSIONS: HaploSCT with TBI-free protocols can be a viable option for heavily pretreated patients with advanced malignancies.